Flow cytometers are known for analyzing and sorting particles and are particularly suited to measure physical and chemical properties of biological materials, such as cells. During operation, a flow cytometer produces a fluid stream that entrains a sample fluid containing particles of interest. These particles may be individually inspected in the fluid stream by a variety of sensing systems or detection devices for classification.
Flow cytometers adapted for sorting additionally provide a mechanism for isolating subpopulations of particles based on their measured or determined properties. Jet-in-air flow cytometers achieve this separation through the creation and isolation of charged droplets containing particles of interest. The particle-containing droplets may be formed from the fluid stream and charged based upon a sort decision and, as they pass through an electrical field produced by deflection plates, their path is redirected into one of several predetermined trajectories for collection. The formation of these droplets may be achieved at a flow cytometer nozzle.
In addition to the function of droplet formation, some flow cytometer nozzles include an interior geometry that influences particles toward a uniform orientation. The orientating function enables analysis and sorting of cells with aspherical properties. As an example, the speeds at which sperm can be sorted into gender enriched populations have been increased, in part, due to the development of an orienting nozzle which presents a larger portion of the sperm to detectors in a relatively uniform orientation.